This invention relates to seed meters. More particularly, this invention relates to rotating disc seed meters.
Seed planters are used in modern high-production farm operations to create a trench in the soil, deposit seeds into the bottom of the trench at accurate intervals, and then cover the trench. Seed planters are pulled behind a tractor and have a plurality of individual planter units arranged side-by-side so a plurality of parallel rows can be simultaneously planted. A conventional corn and soybean seed planter is disclosed in Deckler, U.S. Pat. No. 3,999,690, issued Dec. 28, 1976, which is incorporated by reference. Each individual seed planter unit contains a seed hopper for holding a quantity of seeds, a seed meter for metering the seed, and a seed conveyor through which the seeds pass from the meter to the soil. Each seed planter unit also contains a pair of trench forming discs in front of the drop chute and a soil packing wheel behind the drop chute.
The seed meter disclosed in Deckler employs a rotating disc. The rotating disc contains a plurality of openings in indentations arranged in a circular array which hold the seeds by means of a pressure differential between the seed-holding side of the disc and the opposite side. As the disc rotates, an opening passes through a seed chamber, picks up a single seed, and then releases the seed at a discharge section where the pressure differential is reduced. In this type of seed meter, it is very important that each opening is xe2x80x9csingulated,xe2x80x9d i.e., that each opening contain one and only one seed. If an opening does not contains a seed (a xe2x80x9cblankxe2x80x9d) or contains two or more seeds (a xe2x80x9cmultiplexe2x80x9d), the planted field will contain plants that are not optimally spaced.
Uneven seed spacing also occurs with the Deckler seed meter because the seeds are released from the meter at varying trajectories. The variance in trajectories creates a difference in the time it takes the seed to pass through the seed conveyor. These differences, in turn, cause the interval between planted seeds to vary. The variance is increased as the speed of the tractor pulling the planter increases.
Stufflebeam et al., U.S. Pat. No. 5,848,571, issued Dec. 15, 1998, which is incorporated by reference, discloses a rotating disc seed meter with a singulator assembly. The singulator assembly is stationary and includes seed engaging members arranged on opposite sides of the path of travel of the openings in the seed disc. If two or more seeds are held at a single opening, Stufflebeam et al. state that the singulator assembly helps to dislodge all but one. However, the singulator assembly plays no role in preventing blanks.
Accordingly, a demand exists for a rotating disc seed meter that improves singulation by reducing blanks and by reducing multiples. A demand also exists for a rotating disc seed meter that reduces the variation in seed intervals by reducing the variation in seed trajectory.
The general objects of this invention are to provide an improved rotating seed meter and an improved rotating disc for such a meter. One more particular object is to provide a seed meter that improves singulation by reducing blanks and by reducing multiples. Another more particular object is to provide a seed meter that reduces the variation in seed intervals by reducing the variation in seed trajectory.
I have invented an improved disc for a rotating disc seed meter. The disc comprises a circular array of openings against which the seeds are held on one side by means of a pressure differential as they are carried from a seed chamber to a seed discharge, and a plurality of tabs on the seed-holding face of the disc, a tab associated with each opening, each tab being positioned radially adjacent the trailing edge of its associated opening to improve singulation by reducing blanks and multiples, and to reduce variation in seed intervals by reducing the variation in seed trajectory.
I have also invented an improved rotating disc seed meter. The meter comprises (a) a housing comprising a seed inlet, an internal seed chamber, a seed discharge, and an opening communicating with a pressure differential source; and (b) a rotating disc supported within the housing. The rotating disc provides a partial seal between the seed chamber and the pressure differential source. The rotating disc comprises a circular array of openings against which the seeds are held on one side by means of a pressure differential as they are carried from a seed chamber to a seed discharge, and a plurality of tabs on the seed-holding face of the disc. A tab is associated with each opening. Each tab is positioned radially adjacent the trailing edge of its associated opening to improve singulation by reducing blanks and multiples, and to reduce variation in seed intervals by reducing the variation in seed trajectory.
The seed meter enables seeds to be placed into an underlying trench at optimal intervals for two primary reasons. First, the seed meter improves singulation by reducing blanks and by reducing multiples. Second, the seed meter reduces the variation in seed intervals by reducing the variation in seed trajectory.